Resonant Activation from the Zero-Voltage State of a Current-Biased Josephson Junction

The lifetime $\tau$ of the zero-voltage state of a current-biased Josephson junction in the thermal limit has been measured in the presence of a weak microwave perturbation. When the microwave frequency is close to the plasma frequency of the junction, the junction is "resonantly activated" out of the zero-voltage state, with a corresponding reduction in $\tau$. The results are well explained by numerical simulations.